A mattress normally includes a coil spring unit defined by a plurality of interconnected coil springs which are united to each other and to upper and lower polygonal frame wires which impart a generally rectangular configuration to the coil spring unit. An upper or top mattress pad and a lower or bottom mattress pad, each formed of multiple layers or plies of materials stitched together, and a like narrow peripheral mattress pad, also formed of multiple plies or layers, are assembled to entirely encapsulate the coil spring unit and form the mattress.
The top, bottom and peripheral mattress pads are each formed as a laminate which might, for example, include a backing material layer, a foam material layer, a fiber material layer and a ticking layer, all stitched together by stitching of a conventional "quilt" pattern or design. The materials of the latter layers, the thicknesses thereof, etc. all contribute to such characteristics as softness, breathability, wear, etc. However, irrespective of the particular layers, it is important that the upper mattress pad and the lower mattress pad are manufactured as inexpensively as possible, yet provide the best mattress characteristics possible at the lowest equitable cost over the longest mattress life possible.
A typical conventional mattress corresponding to the mattress just described is disclosed in U.S. Pat. No. 5,317,768 granted on Jun. 7, 1994. The patent discloses a spring component and at least a top surface component formed as a laminate with the outer layer being the ticking or cover fabric, the next inboard layer being a fiber layer, the third layer being a convoluted foam layer, and the innermost fourth layer being a cotton layer with associated stitching holding all four of these layers together to form a quilted multi-ply mattress pad. The thickness of the fiber layer and the thickness of the convoluted foam layer are said to be matters of design choice, though specific examples of weight per square foot of the polyester fiber and the height of the convoluted foam layer are specified as being illustrative. However, it is generally conceded that the best mattresses providing the most comfort are those which include an appreciably thick layer of convoluted foam. However, foam material, particularly latex (natural rubber) foam is extremely expensive and, therefore, appreciably thick convoluted latex foam layers are found most exclusively in higher end, more expensive mattresses. It would be highly desirable to increase the latex foam content in lower end mattresses (less expensive) if costs could be maintained relatively low during the manufacture thereof such that as an end result virtually all qualities of the mattress are appreciably increased at a moderate or low increase in cost at both the wholesale and retail levels.